1. Field of the Invention
The present invention relates to a display device in which light-emitting elements provided on a pixel-by-pixel basis are driven by current for image displaying, and a method for driving the same. Furthermore, the present invention relates to electronic apparatus including the display device. Specifically, the present invention relates to a drive system for a so-called active-matrix display device in which the amount of the current applied to a light-emitting element, such as an organic EL (electro-luminescence) element, is controlled by insulated-gate field effect transistors provided in each pixel circuit.
2. Description of the Related Art
In a display device, e.g., in a liquid crystal display, a large number of liquid crystal pixels are arranged in a matrix, and the transmittance intensity or the reflection intensity of incident light is controlled on a pixel-by-pixel basis in accordance with information on an image to be displayed, to thereby display the image. This pixel-by-pixel control is carried out also in an organic EL display employing organic EL elements for its pixels. The organic EL element however is a self-luminous element unlike the liquid crystal pixel. Therefore, the organic EL display has the following advantages over the liquid crystal display: higher image visibility, no necessity for a backlight, and higher response speed. Furthermore, the organic EL display is a so-called current-control display, which can control the luminance level (grayscale) of each light-emitting element based on the current that flows through the light-emitting element, and hence is greatly different from a voltage-control display such as the liquid crystal display.
The kinds of drive systems for the organic EL display include a simple-matrix system and an active-matrix system similarly to the liquid crystal display. The simple-matrix system has a simpler structure but involves problems such as difficulty in achievement of a large-size and high-definition display. Therefore, currently, the active-matrix system is being developed more actively. In the active-matrix system, the current that flows through a light-emitting element in each pixel circuit is controlled by an active element (typically a thin film transistor (TFT)) provided in the pixel circuit. Related arts about this system have been disclosed in Japanese Patent Laid-open Nos. 2003-255856, 2003-271095, 2004-133240, 2004-029791, 2004-093682, and 2006-215213.